bgp_print_peers: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/xorp/bin/bgp_print_peers - from package: xorp

You may install the required package with command apt-get install {package}

Error in other languages:
bgp_print_peers: bevel nie gevind nie
bgp_print_peers: comandă negăsită
bgp_print_peers: comando não encontrado
bgp_print_peers: commande introuvable
bgp_print_peers: command not found
bgp_print_peers: käsku ei ole
bgp_print_peers: không tìm thấy lệnh
bgp_print_peers: komanda nerasta
bgp_print_peers: Kommando nicht gefunden.
bgp_print_peers: kommandot finns inte
bgp_print_peers: komut yok
bgp_print_peers: nie znaleziono polecenia
bgp_print_peers: níor aimsíodh an t-ordú
bgp_print_peers: no se encontró la orden
bgp_print_peers: no s'ha trobat l'ordre
bgp_print_peers: opdracht niet gevonden
bgp_print_peers: parancs nem található
bgp_print_peers: perintah tidak ditemukan
bgp_print_peers: príkaz nenájdený
bgp_print_peers: příkaz nenalezen
bgp_print_peers: команда не найдена
bgp_print_peers: командата не е открита
bgp_print_peers: 命令找不到
bgp_print_peers: コマンドが見つかりません